Posted this back in May, https://discussions.unity.com/t/netcode-source-generators-never-finish-in-rider/ without response, been broken forever, it's super annoying having to make a local copy of netcode just to be able to use my own source generators. Pretty sure Enzi reported this earlier as well.
It's because of how netcode is using additional files.
#Netcode breaks user source generators
lapis mica